The present invention relates to the field of fluid dispensing systems. In particular, the present invention relates to an automated and robotic system for providing repeatable, high throughput dispensing of a plurality of fluids.
Fluid dispensing systems are useful in a variety of areas, including the area of preparing fluid mixture samples to be screened for identification of a fluid mixture capable of crystallizing a protein that is, in turn, studied with x-rays to determine its function and the function of the gene encoding it.
With the identification of the more than 31,000 genes of the human genome, the determination of each gene""s role in the functioning of the human body has become of paramount importance. Genes generally function to produce at least one protein, and thus the functions of numerous proteins produced by genes also are studied. Ascertaining protein structure can be an important step in understanding the function of that protein.
One technique for ascertaining a protein""s structure is to obtain high-quality x-rays of the protein""s crystalline structure. To do so, a preliminary step is crystallizing the protein. One technique for protein crystallization involves crystallizing the protein in a fluid mixture formulated to provide a stable crystal structure for that particular protein. Growing protein crystals using such a technique, however, can be difficult and very time consuming. Each new protein crystallization typically requires a unique concentration and mixture of fluids for crystal growth. It can be necessary to screen a protein sample against hundreds or even thousands of available fluid mixtures in order to determine a proper fluid mixture that will crystallize a single protein. For example, finding the proper fluid mixture may require varying the composition of the mixture using a multi-dimensional array of variables, such as different salt and buffer fluids, different concentrations and pH values for each fluid, and different atmospheric conditions.
Screens for suitable protein crystallization conditions are currently conducted manually using skilled technicians. Performing each screen can be a labor intensive process in part because the different fluids into which the proteins are deposited must themselves be deposited in very small amounts into very small fluid reservoirs. The physical act of dispensing such small amounts into such small fluid reservoirs is itself a time consuming and inaccurate process. In addition, the amount of protein available for each individual screen is often limited, and screening fluids used in each screen are typically measured in microliters. This requires a high level of precision and accuracy that can be difficult even for skilled technicians. Reliability and repeatability of each screen is integral to the precision and accuracy of each screen. Accordingly, there exists a need to automate the screening process, and to increase the level of precision, accuracy and repeatability of the process.
Conventional crystallization techniques may require that each protein to be crystallized is screened against numerous different fluid mixtures (typically hundreds, or many thousand) in order to find a proper composition that provides stable crystallization conditions for the particular protein in question. In a manual screening process, a technician is primarily responsible for measuring, mixing, and dispensing each unique fluid mixture. Such a manual process is time consuming and expensive, and therefore the variations of fluid mixtures are often limited because of time constraints in the screening process. Unfortunately, by reducing the granularity of the screen, a less than optimum fluid mixture will likely be selected. Further, such a manual screening process is highly susceptible to human mathematical and measurement errors in fluid preparation. In such a manner, the screen may produce erroneous, unreliable, or unrepeatable results.
Yet another problem associated with screening crystallization conditions is that many of the known buffer fluids, and other fluids used in the screens tend to be highly volatile. These volatile fluids can evaporate or change in character over time. Therefore, it can be difficult to manually prepare a screen having a large number of individual tests because of the time required to deposit the fluids into each well. As the different fluids are deposited in each well, the volatile fluids can evaporate or otherwise change composition, rendering the particular screen inaccurate.
Therefore, there exists a need for a fluid dispensing system that can quickly and repeatedly perform the multiple fluid depositing steps required for large numbers of screens or other types of precise, highly repeated, fluid handling processes.
The present invention alleviates to a great extent the disadvantages of the known protein crystallization and screening techniques by providing an automated system and method of performing multiple fluid depositing steps for high throughput processing protein screening and crystallization.
Briefly, in a preferred embodiment, fluid wells are positioned below a plurality of fluid dispensing devices. For example, syringes may be configured to dispense fluid into the individual fluid wells. The fluid dispensing devices are configured to be positionable relative the fluid wells. This enables different fluid dispensers to be sequentially positionable over a particular fluid well. A controller preferably controls the relative movement between the fluid wells and the fluid dispensing devices. It is preferred that the controller include software that allows operator flexibility in determining the relative movement between the fluid wells and the fluid dispensing devices.
In operation, the controller selectively operates a multi-well vessel transport in one direction and moves the fluid dispensing devices in a second direction. When directed by the controller, a selected fluid dispensing device deposits a determined quantity of a fluid into a selected individual well of the appropriate multi-well vessel.
It is preferred that a plurality of multi-well vessels and fluid dispensing devices be arranged to work in close association with each other so that an increase in throughput is achieved. Accompanying the increase in throughput is an increase in reliability and repeatability, and a decrease in the time associated with fluid deposition. The increased throughput substantially eliminates the conventional problem of having the character of the deposited fluids change as a result of volatility.
In one aspect the present invention features an apparatus for automatically preparing mixtures of fluids in a plurality (e.g., 96, 384, or 1536) of wells of a multi-well holder. The apparatus includes a plurality of fluid dispensing devices capable of being sequentially positioned above the wells. Each fluid dispensing device is capable of dispensing a fluid into a well when the well is positioned below the fluid dispensing device. The apparatus also includes a controller that controls dispensation of the fluid from the fluid dispensing devices and the relative movement between the fluid dispensing devices and the wells.
In preferred embodiments, the plurality of tubes are configured so that 1, 2, 3, 4, 5, 6, 7 or 8 multi-well holders can be beneath the plurality of tubes at the same time. Preferably, the plurality of tubes are configured so that the dispensing mechanisms can deliver the material to 1, 2, 3, 4, 5, 6, 7 or 8 multi-well holders at the same time. The plurality of tubes may be configured so that all of the dispensing mechanisms can deliver the material at the same time. In one preferred embodiment, the moving element has a length of at least n multi-well plates, wherein n is the number of multi-well plates, wherein each multi-well plate has m wells, wherein m is the number of wells, wherein the apparatus processes a multi-well plate every m dispensings even though the multi-well plate is in the apparatus for n times m dispensings. For example, the moving element has a length of at least five multi-well plates, wherein each multi-well plate has 96 wells, wherein the apparatus processes a multi-well plate every 96 dispensings, even though the multi-well plate is in the apparatus for 480 dispensings. The dispensor controller preferably directs the delivery of the material from each fluid container to each multi-well plate, for example the dispensor controller may direct the delivery of the material from each of at least eight fluid containers to each of at least five multi-well plates.
In another aspect, the invention features a system for efficiently loading mother liquors in a plurality of multi-well sample plates for a course screen, the plurality of sample plates arranged with corresponding columns aligned, the system including: (a) a plate arranging area configured to receive the plurality of sample plates; (b) a plurality of fluid containers, each fluid container holding a predetermined mother liquor mixture; (c) a plurality of syringes arranged in an array, the array, each syringe being in fluid communication with an associated one of the fluid containers; (d) a drive mechanism constructed to sequentially position the syringes in the array directly over each column of wells in the sample plate; (e) a dispensing mechanism associated with each syringe; and (f) a fluid controller communicating to the dispensing mechanism; wherein the fluid controller directs the dispensing mechanisms to deliver a quantity of each associated mother liquor into each sample well in a column before the drive mechanism moves the syringe array to a next column.
In preferred embodiments the plurality of syringes are configured so that 1, 2, 3, 4, 5, 6, 7 or 8 sample plates can be beneath the plurality of syringes at the same time. The plurality of syringes preferably are configured so that the dispensing mechanisms can deliver the material to 1, 2, 3, 4, 5, 6, 7 or 8 sample plates at the same time. The plurality of syringes may be configured so that all of the dispensing mechanisms can deliver the material at the same time. In one preferred embodiment, the system includes a moving element that has a length of at least n sample plates, wherein n is the number of sample plates, wherein each sample plate has m wells, wherein m is the number of wells, wherein the system processes a sample plate every m dispensings even though the sample plate is in the system for n times m dispensings. For example, the moving element has a length of at least five sample plates, wherein each sample plate has 96 wells, wherein the system processes a sample plate every 96 dispensings, even though the sample plate is in the system for 480 dispensings. The fluid controller preferably directs the delivery of the material from each fluid container to each sample plate, for example, the dispensor controller directs the delivery of the material from each of at least eight fluid containers to each of at least five multi-well plates.
In another aspect, the present invention provides a method for automatically preparing a mixture in a well of a multi-well holder. The method involves the steps of: (a) moving the multi-well holder so that the well is positioned below a fluid dispensing device; (b) dispensing fluid from the fluid dispensing device into the well; and (c) repeatedly moving the multi-well holder so that the well is positioned below a next fluid dispensing device and dispensing fluid from the next fluid dispensing device into the well until a predetermined mixture is prepared.
In preferred embodiments, the plurality of syringes are configured so that 1, 2, 3, 4, 5, 6, 7 or 8 multi-well holders can be beneath the plurality of syringes at the same time. The plurality of syringes preferably are configured so that the syringes can deliver the material to 1, 2, 3, 4, 5, 6, 7 or 8 multi-well holders at the same time. The plurality of syringes may be configured so that all of the syringes can deliver the material at the same time. In one preferred embodiment, the sample plates are on a moving element that has a length of at least n sample plates, wherein n is the number of multi-well plates, wherein each multi-well plate has m wells, wherein m is the number of wells, wherein the method processes a multi-well plate every m dispensings even though the method involves n times m dispensings. For example, the sample plates are on a moving element that has a length of at least five multi-well plates, wherein each multi-well plate has 96 wells, wherein the method processes a multi-well plate every 96 dispensings, even though the method involves 480 dispensings. Preferably, a controller directs the delivery of the material from one or more fluid containers to each sample plate. For example, the controller directs the delivery of the material from each of at least eight fluid containers to each of at least five multi-well plates.
Finally, in another aspect, the present invention provides a syringe array for dispensing liquid into a plurality of multi-well sample plates. The syringe array includes a plurality of N syringes coupled into a linear array. N is a whole number multiple of the number of sample wells in one line of each sample well. Each sample plate includes sample wells organized in a geometric pattern. The line may be a row or a column. By way of example, the number of sample wells in a line may be 12 and N may be 96.
In preferred embodiments of any of the aspects of the invention described herein, the footprint of the tubes in the column direction (i.e., the column length footprint) of the multi-well holder is at least 5.030, 10.060, 15.090, 20.120, 25.150, 30.180, 35.210, 40.240, or 45.270 inches long.
It readily will be appreciated that an advantage of the present system is to increase the speed, accuracy and reliability of protein crystallization and processing operations.